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Silversmith needs to raise pH in Watts nickel

2003

Hey all,

I recently started using Watts nickel to obtain a satin finish on door hardware, lamps, etc. I've added a standard wetting agent and a leveling agent specified for a dull finish. I understand that the pH should be between 3.0- 4.2, I've been getting some pitting, so I checked the pH which is 5.0. The question is what to use to raise the pH? Boric acid?

Thanks in advance.

Jon Diamond
silver plater - Berkeley, California

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Although you said 'raise the pH', you meant lower it, didn't you. Boric acid should be kept at just below the saturation point, but lowering the pH may require sulfuric acid.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

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First of two simultaneous responses -- 2003

In a Watts Nickel bath, you can keep the Boric Acid near the saturation point by placing powdered Boric Acid into a clean, de-sized anode bag. (To de-size, run bag through a cycle in a commercial clothes washer, without using ANY soap. Keep bags wet I cotton to prevent shrinkage.) Lowering pH can be done with Sulfuric Acid. The acid MUST be diluted first. This varies according to individual need. Some platers use 1:10 acid:water. Others use l:l acid:water. Remember always carefully pour acid into water. Always wear face shield [affil links] and other necessary safety gear.

Ed Budman [dec]
- Pennsylvania
With deep sadness we advise that our good friend Ed passed away Nov. 24, 2018

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Second of two simultaneous responses --

Watts nickel should have its pH reduced by the addition of sulfuric acid. The boric acid level should be between 30 and 45 g/l, depending on your operating conditions. I personally prefer to run at about 40 g/l. Whilst pitting can be due to an imbalance in pH, it can also be due to many other factors, including lack of wetting agent. I suggest you get a Hull Cell test done once you have the pH under control - this will tell you a lot about what is going on with your pitting.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2003